Patent GB-572806-A (GB)
Title: Process for the simultaneous reduction in olefin content and increase in octane number of olefinic naptha fractions
IPC: C10G35/14
Filed: 1943-05-11
Abstract: <PICT:0572806/IV/1> An olefinic naphtha fraction is contacted at 480-570 DEG  C. with a refractory silica-base oxide cracking catalyst in the absence of added or recycled hydrogen or gas containing substantial amounts of free hydrogen while employing said catalyst at the rate of 5-30 parts by weight of fresh or regenerated catalyst per part of said naphtha, whereby the bromine number is decreased and the octane number increased.  Silica-alumina catalysts obtained by acid treatment of clays of the montmorillonite type or, preferably, by precipitation from suitable solutions may be used. When using a powdered catalyst suspended in the oil vapours, a naphtha fraction, preferably obtained by thermal cracking or reforming, may be fed through a heating coil 6 into transfer line 10 where hot regenerated catalyst supplied through pipe 11 is added in such proportions as to give a catalyst to oil ratio within the specified limits.  The suspension enters chamber 13 containing catalyst maintained in a turbulent state by the hydrocarbon vapours bubbling upwards. Sufficient catalyst is maintained in suspension to give a ratio of oil charged per hour to weight of catalyst in the chamber within the approximate range of 1 to 8.  Separation of the catalyst into a lower dense phase and upper disperse phase separated by a meniscus 14 usually occurs.  Hydrocarbon vapours are continuously withdrawn through separator 15, entrained catalyst being separated and returned to the dense phase by line 16.  They are fractionated in 19 to give a distillate of desired end-point which can be condensed, separated from gases, stabilized, and treated to give a gasoline fraction. Spent catalyst is withdrawn by pipe 24 wherein a rising stream of inert gas such as steam supplied by line 25 maintains it in a fluidized state and removes volatile hydrocarbons.  It is then conveyed through transfer line 28 by oxygen-containing gas supplied through line 29 to regenerator 31 where regeneration is effected by controlled combustion.  Separation into two phases again occurs and vent gases, after separation and return of catalyst by separator 33, leave at 35.  Cooling by means of a coil 37 or by withdrawing part of the catalyst and returning after cooling may be employed.  Additional oxygen-containing gas may be supplied.  Hot regenerated catalyst is withdrawn through pipe 11 where it meets a stream of inert gas such as steam from pipe 38 and is fed to the oil in line 10.  In a fixed bed type of operation, processing is interrupted when the weight of oil passed over the bed per unit weight of catalyst is from 1/30 to 1/5 , and regeneration then effected.  In an example, a thermally cracked 205 DEG  C. end point gasoline is treated with a regenerated SiO2-Al2O3 catalyst to form a suspension with a catalyst to oil weight ratio of 15 : 1.  This is kept in a fluidized state in a reactor at 521 DEG  C. and 0.68 atm. excess pressure, the space velocity being maintained at 2.5.  The separated hydrocarbon is fractionated to give a 150 DEG  C. end-point distillate with a high octane number and lead susceptibility. Specification 551,663 is referred to.